About DayAlmanac

DayAlmanac answers three questions about a day: when it falls, what it is, and who started it. Calendar sites are usually confident about the first and vague about the third, and the vagueness is where most of the errors live.

Where the dates come from

Dates on this site are not typed in by hand. Where an observance follows a stateable Gregorian rule — a fixed calendar date, the nth weekday of a month, a fixed offset from one of those — the table is generated from that rule by a script, and the script is covered by unit tests whose expected values are transcribed from published authorities rather than from the script's own output. A test that checks code against itself passes by construction and catches nothing.

Where an observance follows a lunisolar or religious calendar — Easter, the Hebrew and Islamic calendars, the Chinese calendar — no conversion is implemented here at all. Those dates are transcribed from a published authority and cited on the page. A calendar conversion that is subtly wrong four years out is worse than a short table with a source next to it, because nothing would reveal the error until someone had already planned around it.

Every date table runs at least five years forward. That is partly a convenience and partly a safety margin: if an annual refresh is ever missed, the page degrades slowly instead of going wrong all at once.

Why some entries say "nobody knows"

A large share of the observances people search for were not proclaimed by anyone. They were registered by a company with something to sell, started by one person on social media, or simply appeared on a list and propagated. The convention elsewhere is to cover this with a passive — "has been celebrated since the early 2010s" — which reads like history and is not.

Here the founding of an observance is a required field with two states: traced to a named source, or not traced. When it is traced, the proclamation, registration or founder is named and linked. When it is not, the page says so in as many words. An honest gap is more useful than an invented origin, and it is the one thing a reader cannot get from the sites that rank above this one.

Corrections

If a date here disagrees with a primary source, the primary source wins and the page gets fixed. Corrections go to contact@dayalmanac.com.

Written and edited by Owen Zhang.